The present invention relates to ice making methods and apparatus that have adaptive controls for addressing diverse operating and ambient conditions.
Commercial experience has revealed that productive ice-making systems and functional components may not adapt to diverse ambient conditions or internal operating conditions. One particular type of commercial ice making machine sensing system involves optoelectronic IR (infrared) emitters and detectors used to detect beam blockage in several sensing applications. An optoelectronic IR beam blockage sensor apparatus may detect falling ice pieces during the ice harvesting operation, a level of ice in the ice storage bin representative of a bin full condition, and low or high levels of water in the ice-making sump reservoir to provide signals respectively used with automatic ice making.
Basic optoelectronic sensing techniques have inherent detriments that impede consistent, reliable, and long-term operation. Optoelectronic emitters and detectors are prone to changes in characteristics as a function of changes in operating voltages, currents, and temperature. Optoelectronic emitters are particularly susceptible to detrimental and permanent changes in emission efficiency with age based upon accumulated operation time under conditions of elevated semiconductor junction temperature and high operating voltage or current.
Prior optoelectronic sensor implementations suffer performance degradations due to relatively slowly changing conditions and parameters including operating temperature, component age, degradation of the emitters, misalignment of optical components, mineral haze accumulation on optical lenses, moisture condensation on optical lenses, fog, ambient levels of IR radiation, and the like. The practical result has been the sensor subsystem causing the ice making system to go into a diagnostic fault and shutdown mode that interferes with ice making operation, often due to dirty lenses, and an error indication merely communicates the need for service.
Previous methods of optoelectronic sensing using DC optocoupling and a fixed DC comparator require high emitter drive and high detector gain to sense falling ice under poor optocoupling conditions. This causes a detrimental condition whereby ambient sunlight potentially xe2x80x9cblindsxe2x80x9d the optodetector due to output saturation, thus losing the capability to detect relatively small changes in signal level that occur when a slight dynamic optocoupling reduction is caused by a falling ice piece, and reduces capability to distinguish such an event from other ambient conditions and changes in ambient conditions. Detector blinding due to output saturation is cause for the ice making system to go into shutdown to protect itself from potential damage.
False sensing of ice via a previous optoelectronic method was possible because sensing methods implemented quick controller microprocessor interrupts set by a single false detection of an ice obstruction. Electrical noise had the potential to set the interrupt flag, thus causing a false sensing of the presence of ice and the microcontroller algorithm required approximately 200 lines of code and reacted relatively slowly.
A previous problematic optoelectronic sensing system operated pulsed drive of the optoemitter drive circuitry at 120 Hz which is inherently the same frequently as many discharge lamp pulses, electromagnetic fields, and electrical noise producers operating from a 60 Hz power source. Frequency spectra of noise and signal thus have common harmonics that preclude simplified methods to filter out the shared 120 Hz noise fundamental and odd harmonics thereof.
Ice machine methods, systems, and apparatus provide numerous control algorithms for both ice seeding and for harvesting operations. To address significant numbers and ranges of types and sizes of ice, and numerous possible ambient operation conditions for ice-making machines, a proliferation of control algorithms with specific programmed operation parameters would be required in previously known systems, thus resulting in excessive machine service.
Additionally, previous fault diagnostics response algorithms have caused ice-making machines to go into a fault response shutdown condition calling for service due to temporary faults. Such temporary faults are caused by such actions as leaving the ice machine door open so that IR optoelectronic detectors are saturated with ambient IR radiation and temporary loss of supply water pressure. In either of these two unanticipated conditions, the default timeout fault response has been to shutdown operation and indicate need for a service call.
Interrelated complexity of ice machine system operation components including sensors, compressor, heat exchangers, ambient conditions, supply water temperature, supply water quality, and the like typically result in less than optimal performance. Previous ice machine operation system, methods, and components typically result in tradeoffs to favor machine safety versus ice production performance. Furthermore, ice machine controller system hardware has been somewhat distributed and separate, each additional feature causing additional hardware and assembly costs due to increased interface wiring, electrical connectors, multiple independent modular assemblies for control, and the like.
The present invention overcomes the above-mentioned disadvantages by providing a method and apparatus for increasing ice machine production capability and reliability by enabling a set of cooperating improvements with adaptive controls to an ice production system. In general, system reliability, performance, and cost improvements are enabled by enhancements such as selection of a microcontroller incorporating flash ROM (read only memory) enabling end-configuration programmability. In addition, selection of a microcontroller containing integral EEPROM memory enables greater adaptive algorithm control and operation parameter modification, reprogrammability, and lower controller cost. Furthermore, an improved communication interface capability and an expanded fault diagnostic data storage may provide for simplified service. The system preferably includes operation history monitoring for performance validation. Integrated control assemblies improve control and lower cost, while the adaptive electronic circuits control optoelectronic sensing components. Additional output drive and associated controls hardware control compressor starting, compressor operation, reduction of compressor output pressure, and heat exchanger blower fan speed. Sensors provide inputs in response to detected conditions including water reservoir high level, water reservoir low level, ice thickness, supply line voltage, ice door closed, and compressor output pressure.
Preferably, the apparatus component improvements that enable system improvements and method improvements preferably include: adaptive optoelectronic emitter and/or detector circuitry, preferably for sensing falling ice pieces during harvest operation and sensing the ice bin full status. Preferably, both such functions are performed by a single set of emitter and detector components, although each set may have multiple emitters and detectors. In addition, optoelectronic sensing of reservoir high and low water levels preferably utilize programmed and adaptive software thresholds based upon sampling and averaging. Furthermore, an alternative modification may be to utilize acoustic and/or vibration sensing of falling ice pieces during harvest operation and standing ice present in the ice chute. In another embodiment, ice mold types harvest ice as one large piece that breaks up when it drops, and a water splash curtain swings aside from the dropping of harvested ice. Preferably a simple and low cost magnet and reed switch sensor system for curtain position indicates the ice harvest.
A capacitive electric-field dielectric proximity sensor for ice thickness senses ice proximity to determine an end of cycle based upon a thickness and amount of ice. Ice making is alternatively determined by contact with vibrating probes such that the vibration frequency lowers as ice growth encompasses said probes. An ice door switch preferably signals a closed status of the ice removal door, and AC line voltage monitoring circuitry may respond to a condition such as voltage or current outside a preferred range, for example, xc2x110% of nominal voltage, for protective shutdown of the system, the compressor and other loads.
A programmable and adaptive water quality sensor, based preferably upon at least one principle including optoelectronic turbidity, electroconductivity, and/or dielectric property determines the need for purging the water reservoir of undissolved and/or dissolved minerals. This provides an adaptive purge cycle that may purge more or less often than per each default, where each default may be a predetermined number of cycles and/or an ice making duration time since the last purge cycle.
Preferably, communication hardware for simplified service interface inputs, outputs, and controller reprogramming may be provided.
For reduced compressor outlet pressure during compressor motor startup to ease starting current transients and increase compressor motor control relay contact life, the controller 70 controls pressure relief in response to motor start up command. For example, the controller""s response may be actuating one of a plurality of valves where each of the molds in a plurality of molds includes an evaporator valve, or actuating a dedicated bypass valve. For improved performance and/or component life of the ice machine compressor motor, associated power switching components, and/or other devices sharing the power line, compressor unloading is the preferred means of system improvement. Such technology is commonly owned and fully described in U.S. Pat. No. 5,950,439 Methods and Systems For Controlling a Refrigeration System. Preferably, a solid state relay actively controls a compressor motor starting coilxe2x80x94preferably with controlled ON-switching at peak line voltage to reduce peak starting currents into the inductive load. Preferably, a positive temperature coefficient (PTC) resistor is installed in series with compressor motor start coil to protectively limit motor heating associated with repetitive starting and/or excessive starting time.
Incorporation of a dump valve module part of ice machine into an ice machine controller module improves the system for smaller size, better control, and lower cost. Preferably, solid state drive circuitry enables switched speed drive control of compressor and/or fan motor loads for enhanced operation performance. Examples of variability provided by this control include efficiency of operation, highest ice production, quiet operation, clearest ice production, etc. For updating program algorithms, a portable smart card memory may be utilized by a service technician. For example, a 4 Mbyte EEPROM versus typical 8 Kbyte ROM in microcontroller memoryxe2x80x94enables field upgradable reprogramming based upon fault diagnostics, operation performance history, ice machine type, and/or ice machine environmental conditions for improved fault detection and response, improved operation history data storage, and improved fault response such as repeated and extended retry versus system shutdown. Increased controller capability may be provided by enhanced microcontroller memory size, EEPROM memory, and the communication interface for polling of memory and for reprogramming.
Method improvements enabled by intelligent adaptive utilization of said improved system capability result in net productivity and reliability gains. A programmable time duration delay occurs after compressor turn-on to allow prechilling of the evaporator plate/ice making molds, after which time duration water circulation is startedxe2x80x94for more reliable ice seeding and for more controlled water cooling conditions for monitoring of reservoir water temperature cooling rates as discussed below. A programmable number of refilling water reservoir steps occur during a complete ice making cycle based upon system hardware configuration of reservoir size, type of ice molds, and number of ice molds. A programmable and adaptive reservoir water temperature is set, at which temperature an ice seeding operation occurs. A programmable reservoir water temperature is set, below which temperature warmer makeup water is added to the reservoir to avoid ice slush formation. A programmable reservoir water temperature cooling rate is set, above which rate warmer makeup water is added to the reservoir to avoid ice slush formation.
A programmable and adaptive time duration is set for which the water reservoir level goes from high to low, above which duration an extended duration harvest cycle is performed. A programmable and adaptive time duration is set to sense a last falling ice piece during harvest cycle, above which time duration an extended harvest cycle is performed. An over/under dual ice machine configuration shares a harvest sensor whereby both ice machines stop production based upon a bin full condition.
A side-by-side ice dual ice machine configuration shares a cycle timing control whereby both ice machines coordinate ice making cycles to the cycle time of the slower ice production speedxe2x80x94for the purpose of precluding customer service complaints about dissimilar production rates. Preferably, a programmable and adaptive time duration is set for water circulation discontinuation during ice seed operation. Preferably, use of purge valve vs. reliance upon an overflow stand pipe for water purge operation more aggressively expels reservoir water containing contaminants. Preferably, fault detection history data are stored for moving time windows immediately before and during soft and hard fault conditions to augment service troubleshooting. Preferably, operation performance history data and statistics are stored in system memory for performance evaluation and study pursuant to developing system hardware and/or software improvements.